Bleach is Very Bad for Mold on Porous Surfaces
Bleach isn’t your best option when it comes to mold removal. In some cases, on porous surfaces specifically—including wood and grout tile flooring—the active ingredients within bleach evaporate fastest, leaving only water behind to seep deeper into these surfaces, where it helps mold growth rather than inhibiting it.
Bleach is Okay for Non-Porous Surfaces, Small Mold Spots (Toilets, Tub, Etc.)
In a few limited areas and where mold growth is limited to small visible patches or streaks, using bleach is easy and effective: Bleach should only ever be used on non-porous surfaces, like your toilet bowl, toilet tank, or a bathtub.
Don’t Mix Bleach and Ammonia = Toxic Fumes
The U.S. EPA says using bleach for routine mold cleanup is not recommended: “The use of a chemical or biocide that kills organisms such as mold (chlorine bleach, for example) is not recommended as a routine practice during mold cleanup.“
But, it adds that “There may be instances, however, when professional judgment may indicate its use (for example, when immune-compromised individuals are present).
The EPA advises that if you are going to use bleach to clean up or remove mold, that you never mix it with ammonia [or other cleaning solutions or detergents that contain ammonia] as that creates toxic fumes.
Many Clients Call Us After Bleach Failed to Fix Mold Problem
In our years of experience at Mold Solutions, treating mold in homes all across the Tampa Bay area, we’ve heard from several (6-8) clients who “treated” mold with bleach, only to later find out that bleach didn’t tackle the problem, and that it may have even made it worse over time — whether because bleach is 94-95 percent water, or because using bleach is a bit like painting over mold: Neither solution is actually effective.
Mold has to be removed — not bleached or painted over.
And the source of water that caused the mold to grow has to found and fixed.
Or the mold is highly likely to grow back again. And then you will have to call a mold remediation company, and spend more than you probably want to. Prevention is always the best approach to mold.
Bleach is 95% Water, and Not Great for Mold Removal ~99% of the Time
Bleach is made up of anywhere from 90-95 percent water. Water encourages mold growth. So, bleach is a bad idea for most mold-related applications. Here’s why:
- It’s Ineffective & Even Harmful on Porous Surfaces: The active ingredients within bleach that kill mold can’t easily penetrate porous surfaces like wood, drywall, grout, and fabrics. Instead, they evaporate and leave only water behind—which seeps deeper into the surface. Mold’s root system (called mycelium) can grow deep into these materials, so you’re basically watering them rather than killing the.
- Bleach Might Cover Up a Mold Problem: Bleach might remove the mold’s color on the surface, making it seem like it’s been treated or removed, but the water content in the bleach can actually seep into the pores and feed the mold’s roots, leading to more growth below the surface. Like a coat of pain that covers the problem!
- Toxic Fumes and Health Risks: Bleach produces harsh fumes that can irritate the eyes, lungs, and skin. When mixed with ammonia or other household cleaners, it can create toxic gases called chloramines, which can be extremely dangerous to inhale.
- Damage to Materials: Bleach can corrode or damage the materials it’s used on, especially if they are porous. It can weaken fibers, cause discoloration, and break down the finish on various surfaces.
- Partial Solution to a Mold Problem: Bleach doesn’t tackle or treat the underlying moisture problem that led to mold in the first place. To effectively deal with mold, you have to find and fix the moisture source that caused it to grow.
For nonporous surfaces like a toilet bowl, bleach can be effective in killing mold on the surface. It’s important to ventilate the area well and follow safety guidelines, such as wearing gloves and avoiding mixing bleach with other cleaning agents. However, for a long-term solution to mold issues, especially on porous surfaces, it’s better to use products specifically designed for mold remediation or to consult with a professional who can assess and treat the mold problem comprehensively.
